Finally made the AJAX Chat to a usable Plugin for Q2A. Now has separate chatroom for each Q2A category. Chat can be Shown/Hidden by user. You can download it from here:
Provides a sidebar widget which shows chat for logged in users and google ad for others. For google ad to work, please set Adsense ID in the Basic AdSense plugin.
Also provides a Chat Page and a Chat log page which can be searched for previous chats.
Special thanks to Sebastian Tschan for AJAX chat and also Digitizer.com for Integration Instructions with Q2A